acute Inflammation Flashcards
What are the signs of acute inflammation
Heat
Redness
Swelling
Pain
Loss of function
Define acute inflammation
Redundant, complex, adaptive & protective response of vessels, resident cells & leucocytes to noxious stimuli
How does acute inflammation work?
Inflammation brings cells & molecules of host defence from circulation to sites where they are needed, in order to eliminate offending agents & repair tissues
Lasts hours to days
Give examples of causes of acute inflammation
Infections (bacterial, fungal, viral, parasitic) & microbial toxins
Tissue necrosis, ischemia, trauma, physical & chemical injury, irradiation
Foreign bodies
Immune reactions
What are the morphologic hallmarks of acute inflammation?
Dilation of blood vessels
Activation & recruitment of leucocytes
Active exudation of fluid in extravascular tissue
What are the mediators in acute inflammation & where are they produced?
Vasoactive amines (histamine, serotonine)
- released/produced by mast cells, basophils, platelets
Inflammatory lipids (prostaglandins, leukotrienes)
- produced by mast cells, leukocytes
Complement (C5a, C3a)
- produced in liver
Cytokines (IL-1, TNF, IL-6)
- produced by macrophages, endothelial cells, mast cells
Which inflammatory mediators cause vasodilation in acute inflammation?
Inflammatory lipids (prostaglandins, leukotrienes)
Which inflammatory mediators cause increased vascular permeability in acute inflammation?
Vasoactive amines
Complement (C5a, C3a)
Inflammatory lipids
Cytokines (IL-1, TNF)
Which inflammatory mediators cause leukocyte recruitment & activation in acute inflammation?
Inflammatory lipids
Complement
Cytokines
Which inflammatory mediators cause pain in acute inflammation?
Inflammatory lipids
Which inflammatory mediators cause tissue damage in acute inflammation?
Release of neutrophilic cytoplasmic granular content (enzymes)
Reactive oxygen species (produced by neutrophils & leukocytes)
What are the possible consequences of acute inflammation
Complete resolution
Scarring or fibrosis
Progression to chronic inflammation
describe complete resolution as an outcome of acute inflammation
Complete resolution happens when:
- injury is limited in extent
- There is minimal tissue destruction & damaged parenchymal cells can regenerate
This leads to clearance of offending agent & full tissue regeneration
describe scarring/fibrosis as an outcome of acute inflammation
Scarring (fibrosis) occurs when:
- There is substantial tissue destruction
- inflammatory injury affects tissues incapable of regeneration
- Fibrin exudation in tissues or serous cavities (pleura, peritoneum) can’t be cleared
In these cases, connective tissue replaces damaged area, forming mass of fibrous tissue
describe progression to chronic inflammation as an outcome of acute inflammation
Acute inflammation becomes chronic when:
- injurious agent persists
- There is interference in normal healing
Describe acute phase response in acute inflammation
systemic reaction to acute inflammation, involving:
- Pyrexia (fever)
- Leukocytosis (increased WBC count)
- Metabolic changes
- Changes in plasma proteins (acute phase proteins, APPs)
How is acute inflammation similar to a dripping tap?
Leakage of inflammatory cytokines acts both locally & systemically
This “dripping effect” triggers widespread systemic changes
Continuous release of inflammatory mediators leads to acute phase response
What causes pyrexia?
Fever is caused by increase in hypothalamic set point, leading to elevated core body temp
Fever is triggered by exogenous or endogenous pyrogens, which activate host immune response
Describe the pyrexia pathway
- Exogenous pyrogens (e.g. bacteria) & endogenous triggers (e.g. phagocytosis, tissue damage, immune complexes) stimulate:
- Neutrophils & Macrophages, which release:
- Endogenous pyrogens (IL-1, TNF, IL-6), leading to:
- Increased production of PGE₂ (Prostaglandin E₂), which acts on:
- Hypothalamus, increasing body temp via vasoconstriction & shivering
How can pyrexia be regulated?
NSAIDs act as antipyretics by inhibiting PGE₂ synthesis, reducing fever
What is a biomarker?
biological molecule that is objectively measured & is indicator of normal or abnormal process, or of a condition or disease
What are the positive APP biomarkers of inflammation?
What are the negative APP biomarkers of inflammation?
What are the types of exudate in acute inflammation?
What is transudate in acute inflammation?
Extravascular filtrate of protein & cell poor fluid
Caused by increased hydrostatic pressure or due to decreased colloido-osmotic pressure (or combination)
It is accumulated in body cavities & extracellular compartments
Fluid appears grossly clear & watery
